Readers' comments

Everything that is being discussed ignores the really big problem. For renewable energy to play anything but a small part we need a technology that can store energy efficiently and cheaply for periods of days, weeks and months. No such technology exists nor is it is anywhere on the horizon.

Long-term storage is needed because, in many countries, wind blows in the wrong season, or it doesn't blow at all for a period of several days or a week and, as everyone knows the sun shines brightest at midday and not much at 4pm when peak demands start to pick up. Not only that, but a few cloudy days really spoil things.

Hydro pumped storage schemes store electricity for between 6 and 10 hours. To build a scheme that would store it for a longer period means having huge upper and lower lakes separated by about 700 m in vertical height. There are very few sites in the world suitable for this. And even if they were, it is going to be expensive and inefficient.

But we do have the ability to store energy for long periods at low cost and efficiently in coal stockpiles, gas storage structures and stockpiles of nuclear fuel. All these will do the job at a reasonable cost and probably, less environmental impact.

Heavily subsidised renewable energy technologies are very expensive method of generating electricity and do very little towards reducing carbon dioxide. Not that this is needed in a world that is, for sure, cooling which, in turn, proves that carbon dioxide does not cause dangerous man-made global warming.

According to a recent report from Pike Research global investment in energy storage technologies is to reach $122 Billion by 2021. While a recent report from KEMA predicts the U.S. grid energy storage market to quadruple to 4 Giga Watts by 2016. In other words, this is looking like one of the fastest growing and globally critical business sectors to come by in a long time. Daily news of this sector on Twitter @PowerStorageCo

Sirs--your article seemed to be written around a few technologies but wasn't comprehensive. One I'm aware of is flywheel technology or kinetic energy storage. These systems have the abilty to store pretty large amounts of energy (although cost per kwh might be higher than the water systems like Gravity Power, not sure). However, key benefits are perceived to be very fast storage and release, easier control since they are essentially generators, and added advantages of frequency control. Any particular reason you did highlight demonstration projects using these technologies?

Traditionally, electrical power needed to be generated, transported and consumed at the same time. Energy storage shifts this sequence so electricity does not need to be consumed at the same time it is generated, which in turn allows greater use of renewable energy sources—which often aren’t available to generate electricity at the exact time the electricity is in demand. Energy storage can also improve electric service reliability, shift and reduce peak loads, increase grid efficiency, improve grid stability, and enable arbitrage.

Utilities are today using various energy storage mediums, including bulk battery-based storage at the substation level. Investments in these systems have been justified by avoided costs to construct new transmission lines—a process that can take upwards of a decade or longer—and improved reliability for utility customers served by these energy storage systems. More recently, utilities have begun deploying distributed stored energy sources much closer to the point of consumption within the community.

The challenge is that even though the technology is advancing quickly, the regulatory environment is built for the traditional “flow down” of power from centralized conventional generation through transmission and distribution lines to the consumer. Utilities are typically unable to recover the full value provided by stored energy systems—they‘ll recover some of the investment based on reliability benefits, yes, but they aren’t receiving a payback on the ability to break the traditional generate-transport-consume sequence. There is a real value to this time shifting, including savings from building out transmission grids and other generation assets need to support peak demand, along with the ability to use cheaper stored electricity when compared to peak power prices. Stored energy systems also support grid optimization technologies that reduce the amount of electricity lost during distribution and thus improve energy efficiency, but again, regulations aren’t valuing these benefits properly. Our regulatory environment needs to catch to ensure there’s an appropriate return on investment in energy storage, one that reflects the true value of these technologies.

The rail storage concept poses an interesting question - what is the ideal slope of the ramp on which the train runs? Do they seek the steepest naturally-occurring slope possible, or is there a particular sweet spot? How does rolling a train up and down a slope compare in efficiency to lifting and lowering a giant boulder in a pit?

If the velocity is kept low so that rolling and/or air resistnace is a small factor, then vertical would be best--winch the cars straight up in the air on a crane, let them down later. Or build a building with a large elevator shaft (NASA has some). Rolling modified rail cars has the appeal that you can build it with nearly off the shelf parts, but probaly isn't the best solution.

There won't be a solar revolution (since wind is limited in its widespread deployment and progresses are slim compared to the potential of solar) without a storage revolution.

I'm not anxious about the first one: technological breakthroughs will be there. But the second one is a lot more tricky.

Even if you have a massive solar generation network you have to use a storage solution besides. Right now we are using nature's solution to store solar power: fossil fuels. Changing that means simply to cut ourselves from the biggest natural advantage that is fueling our whole economy.

I'm enthusiast about it. Never humankind was in face of such of a challenge and we have the tools to do it. But undermining these facts while we are so fascinated with the so-called IT revolution (I personnaly think the Green Revolution in the 70's with the use of man-made fertilizers was a lot more useful than our appetite with screens) that we don't see it.

Don't misunderstand me: I like my electronic gizmos but we have here a real challenge to be focused on big problems we have to face right now.

That's like saying cars will never work, hint, friction. Resistance losses have to be dealt with, but we have experience with this; the Xiangjiaba-Shanghai HVDC, for example, is only a factor of ten shorter than what you would need to wrap the earth from noon to midnight.

The more labour is automated, the more it can be executed at off-peak times, with smart meters really fine-tuned optimization can come into being. Power-hungry consumer (i.e. daylight-dependent) appliances like AC seem to have another solution, TES.

So both of these developments might turn time-shifting/storage at grid operator level into a vanishing problem (considering that all current technologies seem to be far away from the 100% efficiency that time-shifting labour can supply).

It's interesting that the author didn't add this obvious insight to this piece and almost every commenter here chimed in with some variety of this insight. Tunnel vision or bias here?

Good point, taken. Still, depending on the price of energy, it would make sense in certain industries to tailor labour schedules to energy pricing, if they can. The possibility and incentive will come soon in the form of smart meters and a balanced assessment of the need for storage should take this, TES and other consumer-side handles on the problem into consideration.

Cost-effective storage would make a great deal of sense for a large, energy-intensive manufacturing plant. Keep in mind, however, that the cost savings has to off-set the additional capital cost. That is where the challenge is, not in the concept.

Energy storage does have another value that would make it attractive, Many manufacturing operations are impacted by power fluctuations, such as those that might be caused by a storm. Today, they use gas-powered generators. Energy storage might start by replacing back-up power.

If we had more big electricity consumers whose costs are dominated by variable energy costs rather than capital/ labour, and whose product can be stored in inventory, then we would have automatic demand/ price smoothing.

We do have a few long term trends that will make things easier then. But nothing that would make wind power viable for a large share of generation. To complement wind, we require some mix of nuclear renaissance, expanded coal and batteries of gas turbines. (And note here: we don't want to use up all that natural gas too quickly. The mix needs to be more emphasised on the former.)

As I said, these kinds of facilities tend to be dominated by capital costs, not energy costs. That demands maximum utilization of the facilities. Even for very energy intensive manufacturing such as aluminum refining, it is not possible to let the refining facility cool down.

Perhaps if the whole world practised capital controls like China (negative real interest rates, massive savings and investment), we could profitably expand renewable power generation whilst increasing long run growth rates (endogenous growth theories often attribute productivity growth to falling capital costs - and the rate of innovation there will depend on the size of the market).

@shaun39
Newer data centres come with thermal storage system to utilize night time electricity to create a store of ice or chilled water that could be run off during daytime to provide a very smooth load curve throughout the day.
Also, most data centres have emergency generators that could be run during really tight hours to free up utility power capacity (as sometimes done at California).

This seems like a major opportunity for initial applications of stored energy. Today most of us have a battery-supported ac power module that protects our computer system from transients and short term outages. Telephone companies used batteries for years to provide system-wide back-up. A critical test would be the development of such a storage system that could exploit energy cost variations for a large facility such as a server farm,

There was a feasibility study made to replace generators with grid-rated battery storage (NaS battery system) in a data centre back in 2003, but the battery autonomy of 8 hours was way too short of the 24-hour on-site backup power requirements from potential customers, and the fire marshal didn't like the idea of so much sodium and sulphur in a single building either...

There still is a significant effort on exploiting that technology. I expect that the concerns of a fire marshal can't be an overwhelming impediment. But rather than setting a 24 hr back-up target, this approach would set an economic target - for a given size and cost storage capacity, how much load shifting could be accomplished and what would be the cost savings.

Negative real interest rates just means that interest is below inflation: there is more demand for transferring today's income to the future, than there is supply of profitable investments. The UK has negative interest rates right now (for government).

That can happen for business too: look at China. Incomes and cost of living are rising rapidly, so high earners (in their late 40s & 50s) save a much larger share of current income - they want to avoid decline in living standards during retirement relative to the general population.

The result is very negative real interest rates (interest below inflation). That means investments in high speed rail, wind farms, new nuclear, highways, etc don't even have to return their principal to be profitable (but they must still provide a risk-adjusted return competitive with other available investments).

It's a financial quirk, but there's nothing "forbidden" about it. Given regulatory change, demographic change or technological change, this really could happen worldwide.

If the an institution is loaning out money at a negative interest rate, it is effectively giving money away. That money has to come from somewhere. One impact would be a further increase in inflation, which would devalue the money eventually paid back.

The "solution" China has come up with is a gray market for loans, at high interest rates. It is true that the government, like governments everywhere, subsidize high profile projects. But, like governments everywhere, their choices are dictated by political rather than economic considerations. The US federal government is in the business of making low interest loans to selected industries, and selected beneficiaries within those industries. We read about them in the papers every day.

That doesn't mean that institutions are giving money away: in cash terms, they are investing money at a positive nominal interest rate - they get back more cash than they invest. What you seem to allude to is the impossibility of negative nominal rates, which is true but besides the point.

Negative real rates are simple - you are trading a bundle of consumption today for a smaller bundle of consumption in the future. Depending on market conditions, that can still be a very good deal for soon-to-be-pensioners, anybody wanting to hedge against a reduction in income, etc. The market price of deferred consumption can be either positive or negative.

Generally positive returns to deferred consumption in the past, don't necessarily tell us what will happen as technology, institutions and demography change.

And in China, grey markets are tiny - participants risk the death penalty. The vast majority of savers accept the negative rates provided by state banks. And the vast majority of state bank funds are invested under CCP rules - to state firms and businesses with export orders, typically at negative real rates.

I have a hard time understanding how China differs from the US in this respect. Interest, CD and treasury bond rates are below inflation. These low rates are a form of taxation on whatever wealth one might have accumulated.

The money they get back has less value than what they borrowed out. The difference in value is what they gave away, plus losses due to risk.

Except that it a tax - businesses that borrow pay back less than they borrow in the first place (in real terms). Just as savers receive less.

There is no tax there - the government doesn't take a cut. Chinese banks aren't making outrageous profits either.

It's just that they have moderate inflation, and a low market interest rate.

The fact that returns are so different in China vs outside, is only possible thanks to tight capital controls. Chinese people are desperate to get their money out of China (some of them succeed - which is what balances the capital account to allow China's massive trade surplus). But controls are mostly successful.

If the US wanted to be more like China, it could get there by:
1) cutting the deficit to nothing/ even surplus
2) strictly regulating banks: ban unsecured consumer credit, specify strict minimum collateral requirements for mortgages/ loans
3) cutting social security to nearly nothing

Those 3 things would cut the supply of vehicles for transferring income to the future (dominated by consumer & government devt), while increasing the demand for such vehicles (future-pensioners compensating for loss of social security).

That, with capital controls and a little monetary easing to bring inflation up to 4-6%, might just be enough to achieve permanent negative real interest rates for government, business & infrastructure investment.

It wouldn't be socially desirable though, unless you think that business/ infrastructure investment has big positive externalities or contributes to productivity growth.

The tax is inflation itself in the case of the saver. The value of his savings goes downward every year, as if the government had imposed a tax on his savings. The government takes a cut when they issue treasury notes.

By contrast, when inflation is modest and stable (at 5%, say), it is built into expectations. The government doesn't profit from expansion of the money base - most of the money base is government bonds, and inflation expectations are already built into the rates and refinancing requirements.

The closest thing to what you are talking about is seigniorage (increased demand for notes and coins due to inflation), which is actually pretty trivial in a modern economy - whatever the inflation rate. Even the US, which benefits from dollar notes being used by criminals & black markets everywhere, makes less than 0.1% of GDP this way. With steady 5% inflation, it would remain less than 0.2% of GDP, raised mostly from foreigners, and with declining significance as we tend to use electronic money over cash.

In my opinion, these technologies are a great way to help attack an overall energy problem. As some of these new techniques are having difficulty scaling up, perhaps a company will come out and approach the problem from the demand side and scale down.

I would be interested to see what could be done to scale down these technologies and give consumers the opportunity to provide impetus. From an economical standpoint, instead of trying to store energy until peak hours, large businesses and homes could use scaled down systems to alter when their demand peaks. My office has hundreds of computers that all operate during peak hours. i can only image the money that would be saved if my employer could purchase much of the energy during off peak night hours and release that energy during peak hours when the cost of energy is more expensive.

It would be a good idea to remove the restraints imposed on these systems by their large scale and regulations and bring the energy optimizing technologies to the public .

What if there was no more peak or off peak hours? what if demand was always a constant amount equal to the average current use, we would not only be saving waste, but wouldn't even need to be producing as much as we do now.

We do that now. We store energy in piles of coal, tanks filled with NG, uranium fuel rods and water stored behind dams. The storage capability of energy has always been a primary attribute, since we began storing wood for a fire. Unfortunately, this important feature of an energy technology seems to have been forgotten.

There is a market to avoid consuming electricity at one time: it's called effacement and it's working well.

Companies are signing contracts with intensive energy-consumer industries and when the TSO is struggling to meet the demand they are asking to switch off some factories. BIG factories actually, it has to consume power over 1 MW. To give you an idea it's equivalent to 5,000 computers. So it's easier to target big consumers.

Right now it's a niche market. To achieve a full effacement market and give incentives to smaller consumers like companies or private owners, you have to build a whole system (with a lot of investments) with meters that communicate in both ways (so called "smart" meters, actually it's really the first step to a smart grid) and eventually the possibility to program automatically every big electricity consuming units (servers, cooling and heating units, washing machine, etc.) to switch on/off them at the best price opportunity.

Because right now, even there is a flexible price system, people will have to it themselves or buy expensive technology to achieve those simple tasks remotely.

There is a HUGE market here but deregulation in this very case will be very useful to promote innovation and competition. Right now meters are installed by "official" TSOs and they are not really interested into price optimization for consumers. Surprisingly.

In a sense the situation, in this very case, looks like before the Internet revolution where big companies and regulation didn't allow to enter a new market full with opportunities. (Basically Tesla and Edison would recognize the grid they created decades ago, Bell and other telecom inventors would be amazed with what we did; but the two technologies are not similar, exchanging bits and bytes is way different from equating production and demand at all the time with physical electrons. In a sense telecom networks didn't work without electricity network which is the zero level of the economy)

There are a lot of companies in this field, proposing interesting technology. I won't be surprised that one of them will grow into the new Apple of the future.

Try to control yourself, Tim. Your frustration with your confusion over what people are discussing has gotten out of hand.

Let me try to explain it to you.

Indeed this article does DISCUSS energy storage - even I was able to figure that out. Meanwhile, we waste billions on constructing outdated renewable energy farms and facilities that depend on back-up from conventional energy sources with stored energy capability. We need to stop wasting money and put that money where our mouth is. Our resources should be devoted to developing the technologies that will do the complete job.

What this article is saying without saying it is that the value of solar power is much greater than it is credited with having, precisely because it makes power available at peak times. A factor that ought to be kept in mind when the price of solar electricity is being discussed. No storage is required.

I know this because I have solar panels, which produce far more power on sunny and hot days in summer than on overcast and cool days in winter. Nearly three times as much. Our house produces a surplus in summer, and presumably a big surplus when the sun is up, but uses grid electricity in winter.

That is the reverse of the article's point about Texas wind, because it is more available at off peak times. But here on the east coast, wind is more available during peak times, when the on-shore breeze kicks in. No storage is necessary.

The power New York needs to store comes from Niagara Falls. Less is available during the day, when water goes over the falls for tourists. More is available overnight, when the falls are shut off and all the water goes to power.

The article is trying to tell you the opposite, WT. You refuse to listen, however.

Apparently you neglected to check up when peak energy use occurs. Peak use in the summer typically is 4-7pm, about the time when your solar panels become about as useful as a box of rocks. In the winter, the morning and evening peaks are more pronounced, and even more so as it gets colder. Your panels are running at peak and selling energy back to the power company exactly when they do not want additional power - at noon.

The cost of solar power is primarily due to capital cost, which is many time the capital cost for conventional energy. Those calculated costs neglect the additional cost of the underutilized conventional power plants sitting idle during the few hours a solar panel is useful, and then running at peak power to provide needed energy when the peak needs DO occur.

Noon is far from peak usage, as was claimed. In NYC near where WT appears to be from, peak usage is at 4 pm, when solar panel output is at about 50% rated power. In areas such as Texas most people cut their AC back during the daytime and turn it back on in the evening when they come home from work.

Which planet are you from, wssieia? Here on Earth (at least this part of it) prices for peak electricity has been in place for years. Rates vary from 7¢/kWh off-peak in the winter to 35¢ on-peak, July and August. In the summer, Peak is 3-6 pm. In the winter, it is 5-9am and 5-9pm. A solar panel produces most of its energy 10am-2pm. Note the offset.

The pricing has shifted the load somewhat and has had a significant impact on reducing power use, but has had little effect on the peak time. So, you are right, after all!

TES has a market penetration of over 50%. The legislation introduced and mentioned below will speed up installation of all kinds of storage, but if it fails, it will not destroy the TES market. The TES market is user financed for the most part!

The Electricity Storage Association (ESA) applauded news this week that U.S. Reps. Chris Gibson (R-NY) and Mike Thompson (D-CA) introduced legislation that would create an investment tax credit (ITC) for energy storage technologies of all types and help jumpstart an industry that has enormous potential to increase the reliability, security, and efficiency of the nation's electric grid. The Storage Technology for Renewable and Green Energy Act (STORAGE) Act (H.R. 4096) is the House companion legislation to S. 1845, introduced by Sens. Ron Wyden (D-OR), Jeff Bingaman (D-NM), and Susan Collins (R-ME).

Very interesting article! You state, "In electricity generation, however, aggregates and averages carry little weight." Averages don't mean anything because we use energy when we are awake, working, raising families and so on. One of the biggest contributors to electricity consumption peaking during the day is air conditioning. Air conditioning is also one of the easiest loads to shift. Storing btu's cost a LOT LESS than the energy required to create it!

Thermal energy storage (TES) is never mentioned in the same breath as chemical storage or pumped hydro or CAES. While TES is distributed energy storage, according to KEMA, TES accounts for almost 1 GW of current storage capacity. More than twice of pumped hydro and more than pumped hydro and all other technologies combined. TES is proven, affordable, and many systems last for over 30 years. One system is 99% reusable or recyclable at the end of its service life. That is why TES market penetration is so large relative to the other technology.

You also state, "One problem is that wind energy accounted for 9,500MW of ERCOT’s total capacity, and the wind does not blow all the time. It tends to be strongest at night, when demand is low." TES can provide a load for that renewable wind energy for most of the year.

TES used in buildings creates a hybrid cooling system similar to today's hybrid cars. A standard midsized car has a relatively large engine to provide power in all situations, even though the car is lightly loaded most of the time. Hybrid cars use smaller more fuel efficient engines. When the boost is need to merge, the load is heavy, or traffic is at a crawl, the store energy is used.

Conventional HVAC systems have a "big engine" to handle all loads. All support equipment is sized for this big engine even though cooling system rarely operate at capacity. Hybrid cooling systems with energy storage use a smaller "engine" and smaller support equipment. The capital saved is used to purchase and install TES. The stored energy is used during peak cooling times and or times of high prices. Typically less source energy is consumed and cooling costs can be cut 20-40%.

While TES is not usable at all times of the year like some of the technologies you mention, TES is certainly part of the solution and should be mentioned in the same breath as the grid scale technologies mentioned.

In Britain we have a water problem, too much in the West, not enough in the East. We also have problems with power supply and the matching of supply and demand. And lots of trendy windfarms (one exploded near here in a recent 100 mph gale).

The problem with the water is shifting it, it's heavy stuff, so costly to move. However pumped storage systems need to move water about too. pump it up at night or times of low demand, let it out at peak times. Now if some of those mini-systems were organised end-to end, so that one pumped water up then released it to the next which then.. you get the idea. The water is moved about yet has an intrinsic use while doing so. The west stops seeing so much fresh water flowing into the sea while the east gets its reservoirs and aquifers topped up. And we all get electricity, all the time, including during the 'coronation street' advertising break when the whole nation puts the kettle on, all synchronised by ITV.

Paying for it all is another matter. Maybe the bureaucrats (who are mostly in the East) will get the idea when deprived of the water for that cuppa, or electricity too, for that matter.

"The problem with the water is shifting it, it's heavy stuff, so costly to move"
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Actually it is its heavy weight that makes it interesting to store energy. If there were other liquids that were even heavier (and non-toxic) at normal pressure and temperature conditions, they'd be even better.

The Power Grid is designed for its Maximum Peaks which occur during business hours Monday-Friday. Weekends and Nighttime, power demand markedly falls off as much as 80% from peaks.

Not all Kilowatts are equal. It cost more to produce one more Kilowatt during peak times than during trough times. Reserve capacity at night time is wasted.

Vampires have a very low power grid footprint since they are nocturnal. Insomniacs, nocturnals and nightshift human beings have lower carbon footprints than the daytime variety. But we all can't be zombies.

If educated homeowners and consumers are given basic pro-green energy guidelines, we can make do with less.

Run large energy hungry appliances like washers, dryers, dishwashers, hairdryers, heaters, and plasma TVs only from 7 pm to 7 am during 'trough demand times'.

This requires NO new breakthrough in battery technology, green energy power generators, no smart power grid, or rewiring society. And it costs nothing. And you can still enjoy your appliances and conveniences.

USE YOUR APPLIANCES FROM 700 pm to 700 am.
OR ANYTIME DURING WEEKENDS AND HOLIDAYS.
Save the planet simply by practicing good timing.

The problem is that no one has an incentive to do that. Electricity prices are basically the same through the whole day, except with small differences due to different fixed tariffs but it doesn't match the huge real market price differences during peak hours and night hours.

So we need an incentive. Having a vast network of meters that can adjust the paid price of electricity every 30 minutes would be a huge opportunity to level electricity consumption to a flat line. It doesn't require to install some expensive and fancy smart grid system.

Agreed, Financial incentives work. having government control over price settings can only cause the opposite of efficiency. if the market was allowed to set dynamic prices, we could reduce the overall need for energy.

In most places I am aware of, there are major differences in energy costs, depending on the time of day and the season. Those difference do lead to adaptation of usage, including TES, of a sort. It is typical for a home owner to pre-cool his house before peak rates hit, accept somewhat uncomfortable temperatures during peak hours, and cool again before going to bed.
The major impact, however, is not on total energy usage. That optimized air conditioning cycle uses MORE energy than a constant temperature. The impact is on the need for peak capacity, a significant contributor to energy cost.

I'm not a free market fanatic but state prices over energy are one of the last power some countries still have to seduce people (watch what's happening in France with one of the lowest electricity price in Europe due to nuclear power, brilliant engineers and managers - state-owned nuclear is a good thing here! - and opportunistic politics that keep energy prices low threatening the nuclear advantage to invest and renew its fleet.)

But when you look at energy liberalisation in Europe, prices went up and Bruxelles told before that that was a good thing to lower consumer prices...

We need a good mix between the two. We need a strong state to tell what to do with energy production (nuclear and grid management don't work well with free market and a weak state) but in the same time give enough liberties to increase efficiency, peak shifts, local consumption, storage, etc.